配置了一下memcached

1.memcached是什么?
       memcached is a high-performance, distributed memory object caching system, generic in nature, but intended for use in speeding up dynamic web applications by alleviating database load.
2.下载地址
      http://www.danga.com/memcached/
3.安装
     跟一般的linux软件安装一样 ./configure 然后 make,make install
     需要一个库 libevent
    下载地址:
     http://www.monkey.org/~provos/libevent/
     安装库后创建个链接
     ln -s /usr/local/lib/libevent-1.3b.so.1 /lib/libevent-1.3b.so.1
4.启动
     memcached -u nobody -d -m 50 -l 192.168.0.8 -p 10001
    -u 指定用户
    -m 指定缓存使用内存大小，只是测试，就用了50m
    -l 指定ip地址
    -p 指定端口
5.测试
   memcached是一个数据源，所以与应用是独立的，理论上支持任何语言访问。现在已有的client库可在下面的地址得到:
   http://www.danga.com/memcached/apis.bml
   我们用java测试，jdk为1.6
  

java 代码

import com.danga.MemCached.MemCachedClient;
import com.danga.MemCached.SockIOPool;

public class MemcacheTest {

//   create a static client as most installs only need
    // a single instance
    protected static MemCachedClient mcc = new MemCachedClient();

    // set up connection pool once at class load
    static {

        // server list and weights
        String[] servers ={"192.168.0.8:10001"};

        Integer[] weights = { 3 };

        // grab an instance of our connection pool
        SockIOPool pool = SockIOPool.getInstance();

        // set the servers and the weights
        pool.setServers( servers );
        pool.setWeights( weights );

        // set some basic pool settings
        // 5 initial, 5 min, and 250 max conns
        // and set the max idle time for a conn
        // to 6 hours
        pool.setInitConn( 5 );
        pool.setMinConn( 5 );
        pool.setMaxConn( 250 );
        pool.setMaxIdle( 1000 * 60 * 60 * 6 );

        // set the sleep for the maint thread
        // it will wake up every x seconds and
        // maintain the pool size
        pool.setMaintSleep( 30 );

        // set some TCP settings
        // disable nagle
        // set the read timeout to 3 secs
        // and don't set a connect timeout
        pool.setNagle( false );
        pool.setSocketTO( 3000 );
        pool.setSocketConnectTO( 0 );

        // initialize the connection pool
        pool.initialize();


        // lets set some compression on for the client
        // compress anything larger than 64k
        mcc.setCompressEnable( true );
        mcc.setCompressThreshold( 64 * 1024 );
    }

    public static void bulidCache(){
        mcc.set( "foo", "This is a test String" );
        TestObj obj = new TestObj();
        obj.setId(new Long(1));
        obj.setName("test");
        mcc.set("testObj", obj);
    }

    // from here on down, you can call any of the client calls
    public static void output() {
        //
        String bar = (String) mcc.get( "foo" );
        System.out.println(bar);
        TestObj obj = (TestObj)mcc.get("testObj");
        System.out.println(obj);
    }

    public static void main(String[] args){
        bulidCache();
        output();
    }


}

java 代码

import java.io.Serializable;

public class TestObj implements Serializable {

    /**
     *
     */
    private static final long serialVersionUID = 1L;
    private String name;
    private Long id;
    /**
     *
     */
    public TestObj() {
    }
    public Long getId() {
        return id;
    }
    public void setId(Long id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }

    public String toString(){
        return "id:"+this.getId()+";name:"+this.getName();
    }
}

从faq上找了段代码，稍做改动。

运行，成功输出：

This is a test String
com.danga.MemCached.MemCachedClient Sat Jul 14 18:59:46 CST 2007 - ++++ deserializing class net.teamhot.memecache.TestObj
id:1;name:test

中间两行是日志。
把buildCache方法注释了，再运行，成功。

如果是两种语言共享cache，要注意对象的持久化方式。

6.可能遇到的问题
   如果连接不成功请用telent测试服务器端口是否能连接通。连不通请更改服务器的防火墙设置，或者干脆把防火墙关闭了。

   /etc/init.d/iptables stop

    今天就到此为止。改天找几台服务器测试一下memcache的性能。